Process for preparing biphenylamines from anilides by ruthenium catalysis

ABSTRACT

The present invention relates to a novel process for preparing substituted biphenylamides of the general formula (V) 
     
       
         
         
             
             
         
       
         
         
           
             characterized in that 
             anilides of the formula (II) 
           
         
       
    
     
       
         
         
             
             
         
       
         
         
           
             in a solvent other than tetrahydrofuran, 
             are reacted with an organoboron compound of the formula (III) 
           
         
       
    
     
       
         
         
             
             
         
       
         
         
           
             in the presence of a catalyst system consisting of a ruthenium catalyst, an activator, an oxidizing agent and a metal triflate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisonal of U.S. patent application Ser. No. 15/305,865, filed 21 Oct. 2016, which is a § 371 National State Application of PCT/EP2015/058636, filed Apr. 22, 2015, which claims priority to European Application Nos. 14166058.9, filed Apr. 25, 2014, and 14189192.9, filed Oct. 16, 2014. The disclosures of the priority applications are incorporated in their entirety herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a novel process for preparing substituted biphenylamides and, in a further optional stage, biphenylamines.

Description of Related Art

Biaryl compounds, especially biphenyl compounds, are of industrial significance as fine chemicals, intermediates for pharmaceuticals, optical brighteners and agrochemicals.

A method possible in principle for preparation of biaryl compounds in transition metal-catalysed cross-coupling is that of double C—H activation (see, for example, S. L. Buchwald et al, Org. Lett. 2008, 10(11), 2207-10; F. Glorius et al., Angew. Chem. Int. Ed. 2012, 51, 2247-51; WO 2014/019995). Although these methods dispense with the synthesis of a boronic acid, for example, as a starting compound, they have serious disadvantages. For instance, costly palladium or rhodium complexes are typically used as catalysts. Moreover, the generally low reactivity of C—H bonds frequently leads to selectivity problems (functionalization of one C—H bond in the presence of other C—H bonds). In addition, there is competition between hetero- and homo-coupling.

Moreover, it is already known that biphenyl derivatives can be prepared from phenylboronic acids and phenyl halides by a Suzuki or Stille coupling, i.e. by a palladium-catalysed reaction (cf., for example, WO 01/42223, WO 03/070705, WO 07/138089, WO 09/003650, WO 09/135598).

It is additionally known that biphenyl derivatives are obtained by reacting arylzinc halides with aryl halides (Bull. Korean Chem. Soc. 2000, 21, 165-166).

A disadvantage of these processes is the high production costs. Transition metal-catalysed cross-couplings (for example according to Suzuki) require relatively large amounts of costly palladium catalysts or else (Bull. Korean Chem. Soc. 2000, 21, 165-166) the use of virtually equivalent amounts of zinc which have to be disposed of as waste. Moreover, activation of the zinc requires carcinogenic dibromomethane.

It is additionally known that biphenyl derivatives are obtained by reacting acetanilides with aromatic boronic acids in the presence of palladium catalysts, copper(II) triflate (Cu(OTf)₂) and silver oxide (Ag₂O) (Z. Shi et al., Angew. Chem. Int. Ed. 46 (2007) 5554-8). Here too, the high costs of the palladium catalyst are disadvantageous.

It is likewise known that biphenyl derivatives are obtained by reacting arylurea compounds with aromatic boronic acids in the presence of palladium catalysts and benzoquinone (B. H. Lipshutz et al., J. Amer. Chem. Soc. 132 (2010) 4978-9). Again, the high costs of the palladium catalyst are disadvantageous.

It is additionally known that biphenyl derivatives are obtained by reacting acetanilides with aromatic boronic acids in the presence of ruthenium(II) complexes, silver hexafluoroantimonate (AgSbF₆), Cu(OTf)₂ and Ag₂O (R. K. Chinnagolla and M. Jeganmohan, Chemical Communication, January 2014, accepted for publication).

However, the authors state that the only suitable solvent is tetrahydrofuran, while other solvents preferred in industry that are mentioned, for example methanol, toluene or dimethylformamide, are described as entirely ineffective, i.e. without conversion for the purposes of the disclosure, and so the reaction cannot be carried out by the person skilled in the art and hence is not disclosed either.

SUMMARY

The problem addressed by the present invention was thus that of providing a novel process through which biphenylamines can be obtained with a high overall yield and high purity without the use of costly palladium catalysts and under the industrially preferred reaction conditions, especially with industrially preferred solvents.

The present invention accordingly provides a process for preparing biphenylamides of the general formula (V) and subsequently, in an optional second stage, biphenylamines of the general formula (I)

-   -   in which

-   R¹ is hydrogen, hydroxyl, fluorine, chlorine, C₁-C₄-alkyl,     C₁-C₄-alkoxy, C₁-C₄-alkylthio or C₁-C₄-haloalkyl,

-   R² is C₁-C₄-alkyl, C₆-C₁₀-aryl or C₆-C₁₀-aryl-CH₂—, and

-   X¹ is hydrogen, C₁-C₄-alkyl, C₁-C₄-alkoxy, fluorine or chlorine,

-   X² is hydrogen, C₁-C₄-alkyl, C₁-C₄-alkoxy, fluorine or chlorine,

-   X³ is hydrogen, C₁-C₄-alkyl, C₁-C₄-alkoxy, fluorine or chlorine,

-   characterized in that

-   (1) in a first step

-   anilides of the formula (II)

-   -   in which     -   R¹ and R² are each as defined above,

-   in a solvent other than tetrahydrofuran (THF),

-   are reacted with an organoboron compound of the formula (III)

-   -   in which     -   X¹, X² and X³ are each as defined above,

-   and which is selected from one of the following groups consisting     of:

-   (I) boronic acids of the formula (III) in which     -   Q is a hydroxyl group,     -   m is 2,     -   p is 1,     -   or the anhydrides, dimers or trimers of these boronic acids;

-   (II) boronic acid derivatives of the formula (III) in which     -   Q is F, Cl, Br, I, C₁-C₄-alkyl, C₆-C₁₀-aryl, C₁-C₄-alkoxy or         C₆-C₁₀-aryloxy,     -   m is 2,     -   p is 1;

-   (III) borinic acids of the formula (III) in which     -   Q is OH, F, Cl, Br, I, C₁-C₄-alkyl, C₆-C₁₀-aryl, C₁-C₄-alkoxy or         C₆-C₁₀-aryloxy,     -   m is 1,     -   p is 2;

-   (IV) cyclic boronic esters of the formula (III) in which     -   Q is a C₂-C₃-alkyldioxy radical which, together with the boron         atom to which it is bonded, forms a 5- or 6-membered ring         optionally substituted by one or more C₁-C₄-alkyl radicals,     -   m is 2,     -   p is 1;

-   (V) boronates of the formula (III) in which     -   Q is OH, F, Cl, Br, I, C₁-C₄-alkyl, C₆-C₁₀-aryl, C₁-C₄-alkoxy or         C₆-C₁₀-aryloxy,     -   m is 3,     -   p is 1     -   and the negative charge of the boronate anion is compensated for         by a cation, preferably by a metal cation, the metal further         preferably being selected from metals of main groups 1 and 2 and         aluminium, iron and copper,

-   (VI) triarylboranes of the formula (III) in which     -   m is 0,     -   p is 3;

-   (VII) tetraarylborates of the formula (IV) in which     -   m is 0,     -   p is 4,     -   and the negative charge of the tetraarylborate anion is         compensated for by a cation, preferably by a metal cation, the         metal further preferably being selected from metals of main         groups 1 and 2 and aluminium, iron and copper,

-   in the presence of a catalyst system consisting of a ruthenium     catalyst, an activator, an oxidizing agent and a metal triflate,     where the metal is preferably selected from the group comprising Li,     Na, K, Mg, Ca, Mn, Fe, Co, Ni, Cu and Zn, further preferably from     the group comprising Fe and Ni, and more preferably Fe.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Preferably, Cu and Fe are each in their highest oxidation states, while all other metals except for the alkali metals are preferably in the +II oxidation state.

In an optional second stage, the anilides of the formula (V) thus obtained

-   -   in which R¹, R² X¹, X² and X³ are each as defined above,         are acid- or base-hydrolysed (removal of the [—C(═O)R²]         protecting group on the nitrogen) by known organic chemistry         methods.

Preferably, the protecting group on the nitrogen is removed in the second stage.

In a preferred embodiment, boronic acids are used as the component of the formula (III), and more preferably Q=OH, m=2 and p=1.

C₁-C₄-Alkyl encompasses methyl, ethyl, propyl and isopropyl, butyl, isobutyl and tert-butyl and is more preferably methyl.

C₁-C₄-Alkoxy encompasses methoxy, ethoxy, propoxy, isopropoxy and butoxy and is more preferably methoxy.

In an alternative embodiment, the catalyst system consists of a ruthenium catalyst, an activator, an oxidizing agent and a metal sulphate, where the metal is preferably selected from the group comprising Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) Mg(II), Ca(II) and Al(III), further preferably from the group comprising Fe(II) and Cu(II), and more preferably Cu(II).

The advantage of this embodiment is that the much less expensive sulphates, which are thus of greater economic interest, can be used with only a slightly reduced yield compared to the triflates.

In a further alternative embodiment, the activator of the catalyst system is selected from the group comprising Cu(I) oxide and Cu(II) oxide.

While the alternative embodiments differ in the abovementioned type of metal salt, the specifications of the present description additionally apply to the other reaction parameters and co-reactants. Excluded from this is the fact that THF can also be used as solvent with good yields in reactions without metal triflate.

It is surprisingly possible through this reaction sequence to prepare the biphenylamines of the formula (I) in good yields without the use of halogenated anilides, without use of costly palladium catalysts and under industrially advantageous reaction conditions, especially in terms of the solvents used, which do not have a tendency to form peroxides, unlike tetrahydrofurans.

If N-(4-fluorophenyl)acetamide and phenylboronic acid are used as starting materials, the process according to the invention can be illustrated by way of example by the following formula scheme:

If N-(4-fluorophenyl)acetamide and phenylborinic acid, for example, are used as starting materials, the process according to the invention can be illustrated by way of example by the following formula scheme:

The organoboron compounds of the formula (III) are known in principle and can be prepared by known methods.

Preference is given to the performance of the process according to the invention using starting materials in which the radicals specified are each defined as follows. The preferred, particularly preferred and very particularly preferred definitions apply to all the compounds in which the respective radicals occur:

-   R¹ is preferably hydrogen, fluorine and chlorine. -   R¹ is further preferably fluorine or chlorine, where the substituent     is preferably in the 3, 4 or 5 position, further preferably in the 4     or 5 position and more preferably in the 5 position [cf., for     example, formula (I)]. -   R¹ is more preferably fluorine in the abovementioned positions, most     preferably in the 4 position.

In an alternative embodiment,

-   R¹ is preferably trifluoromethyl, where trifluoromethyl is     preferably in the 4 or 5 position, further preferably in the 5     position, of the respective compound.

In a further alternative embodiment,

-   R¹ is preferably methoxy or methylthio, preferably in the 4, 5 or 6     position, further preferably in the 5 position, of the respective     compound. -   R² is preferably methyl, ethyl, isopropyl, tert-butyl, phenyl or     benzyl. -   R² is further preferably methyl, phenyl or benzyl. -   R² is more preferably methyl. -   X¹ is preferably hydrogen, methyl, fluorine or chlorine. -   X¹ is further preferably fluorine or chlorine. -   X¹ is more preferably chlorine. -   X² is preferably hydrogen, methyl, fluorine or chlorine. -   X² is further preferably fluorine or chlorine. -   X² is more preferably chlorine. -   X³ is preferably hydrogen, methyl, fluorine or chlorine. -   X³ is further preferably fluorine or chlorine. -   X³ is more preferably chlorine.

In a particularly preferred embodiment, one of the X¹, X² and X³ substituents is hydrogen, but it is particularly preferable that adjacent substituents are not both hydrogen.

Preferred embodiments of compounds of the formula (V) in the context of the present invention are (the numbers for R¹ each indicate the position):

R¹ R² X¹ 2 X³ V1 h Me Cl Cl h V2 H MU H Cl H V3 4 Me Cl Cl H V4 F (3) Me Cl Cl h V5 5 Me Cl Cl H V6 Cl (4) Me Cl Cl H V7 Cl (3) Me Cl Cl H V8 Cl (5) Me Cl Cl H V9 Me (4) Me Cl Cl H V10 Me (5) Me Cl Cl H V11 F(4) Me Cl Cl Cl V12 H Me H H H V13 H Me F F F V14 OH (5) Me H H H V15 Et (5) Me H H H V16 OMe (4) Me H H H V17 H Me H OMe H V18 H Me H Me H V19 H iPr H H H V20 H tBu H H H

The anilides of the formula (II) for use as starting materials in the first stage in the performance of the process according to the invention are known or can be obtained by known methods.

The first stage of the process according to the invention is performed in the presence of a ruthenium catalyst. Ruthenium catalysts used are, for example, ruthenium complexes such as [{RuCl₂(p-cymene)}₂], [{RuCl₂(cumene)}₂], [{RuCl₂(benzene)}₂], [{RuCl₂(C₆Me₆)}₂], [Cp*Ru(PPh₃)₂Cl] (Cp*=pentamethylcyclopentadienyl). Preference is given to using [{RuCl₂(p-cymene)}₂].

The amount of ruthenium catalyst can be varied within wide limits. Typically, amounts of 0.1 to 20 mole per cent of the corresponding complex are used. Preferably, 1 to 10 mole per cent of the corresponding complex is used.

The first stage of the process according to the invention is performed in the presence of an activator which generates the actually active catalyst from the ruthenium complex used. Such activators used are typically AgSbF₆, KPF₆, NaPF₆, AgF, AgBF₄. Preference is given to using AgSbF₆, AgBF₄ and KPF₆, particular preference to using AgSbF₆.

The activator is used in amounts of 1 to 4 molar equivalents, based on the ruthenium complex. Preference is given to using 1.5 to 3 equivalents.

The first stage of the process according to the invention is performed in the presence of at least one oxidizing agent, the oxidizing agent used preferably being Ag₂O.

The oxidizing agent is used in amounts of 0.5 to 2 molar equivalents, based on the anilide of the formula (II). Preference is given to using 1 to 2 equivalents.

The first stage of the process according to the invention is performed in the presence of a metal triflate or in the presence of copper(II) sulphate or copper(I) or copper(II) oxide. Metal triflates used are compounds such as copper(II) triflate, manganese(II) triflate, cobalt(II) triflate, nickel(II) triflate, zinc(II) triflate, iron(II) triflate, iron(III) triflate, lithium triflate, sodium triflate, potassium triflate, magnesium triflate or calcium triflate, for example. Preference is given to using the compounds mentioned further up, especially sodium triflate, potassium triflate, manganese triflate, zinc triflate, nickel(II) triflate, iron(II) triflate and iron(III) triflate. Very particular preference is given to using iron triflates and nickel(II) triflate.

The metal triflate (or metal sulphate or copper(I) or copper(II) oxide) is used in amounts of 1 to 4 molar equivalents, based on the ruthenium complex. Preference is given to using 1.5 to 3 equivalents.

The first stage of the process according to the invention is performed in solvents or solvent mixtures selected from the group comprising N,N-dialkylalkanamides, for example N-methylpyrrolidone (NMP), dimethylformamide (DMF) and dimethylacetamide (DMA), dimethoxyethane (DME), methanol, ethyl acetate and water, and mixtures of these solvents.

Preferred solvents or solvent mixtures are those selected from the group comprising N,N-dialkylalkanamides, and further preferably among these N-methylpyrrolidone (NMP), dimethylformamide (DMF) and dimethylacetamide (DMA), and more preferably DMF, most preferably dried DMF (storage over 4 angstrom molecular sieve).

From an environmental point of view, water is a preferred solvent, which surprisingly gave the product in a relatively good yield.

For non-triflate-activated reactions in alternative embodiments, it is likewise possible to use THF as solvent with good yields.

The first stage of the process according to the invention is generally performed at temperatures in the range from 20° C. to 200° C., preferably in the range from 50° C. to 150° C.

In the performance of the first stage of the process according to the invention, generally an excess of organoboron compound of the formula (III) is used for 1 mol of anilide of the formula (II).

The second stage of the process according to the invention, i.e. the elimination of the [—C(═O)R²] protecting group on the nitrogen, can be effected under either basic or acidic conditions by known methods (cf., for example, T. W. Greene, P. G. M. Wuts, Protective Groups in Organic Synthesis, Ed. 3, New York, Wiley & Sons, 1999).

Both stages of the process according to the invention are, unless stated otherwise, generally conducted under standard pressure. However, it is also possible to work under elevated or reduced pressure.

In a preferred embodiment of the process according to the invention, the solvent is an N,N-dialkylalkanamide and the triflate is selected from the group comprising iron(III) triflate and nickel(II) triflate, more preferably iron(III) triflate. It is additionally preferable in this combination that the catalyst is [{RuCl₂(p-cymene)}₂]. Even further preferably, the activator is AgSbF₆ and the oxidizing agent is Ag₂O.

The biphenylamines of the formula (I) are valuable intermediates for preparation of active fungicidal ingredients (cf. WO 03/070705).

The process according to the invention is to be illustrated by the examples which follow, without being limited thereto.

PREPARATION EXAMPLES Example 1 N-([1,1′-Biphenyl]-2-yl)acetamide

In a baked-out closable reaction vessel, a suspension consisting of acetanilide (135 mg, 1.0 mmol), [{RuCl₂(p-cymene)}₂] (30.6 mg, 5.0 mol %), AgSbF₆ (68.7 mg, 0.2 mmol), Ag₂O (232 mg, 1.0 mmol), Cu(OTf)₂ (72.3 mg, 0.2 mmol) and phenylboronic acid (183 mg, 1.5 mmol) in dry DMF (3.0 ml) was stirred in a nitrogen atmosphere at 110° C. for 20 h. The reaction mixture was then diluted at room temperature with EtOAc (75 ml) and filtered through Celite and silica gel, and the filtrate was concentrated. The crude product thus obtained was purified by chromatography on silica gel (n-hexane/EtOAc: 7/3). 162 mg of N-([1,1′-biphenyl]-2-yl)acetamide were obtained as a colourless solid (77% of theory). M.p.=113-115° C. ¹H NMR (CDCl₃, 300 MHz): δ=8.21 (d, J=8.2 Hz, 1H), 7.51-7.30 (m, 6H), 7.24-7.13 (m, 3H), 1.98 (s, 3H). ¹³C NMR (CDCl₃, 75 MHz): δ=168.2 (C_(q)), 138.1 (C_(q)), 134.6 (C_(q)), 132.2 (C_(q)), 130.0 (CH), 129.1 (CH), 129.0 (CH), 128.2 (CH), 127.9 (CH), 124.3 (CH), 121.7 (CH), 24.4 (CH₃). IR (neat): 3284, 3230, 3054, 3027, 1658, 1531, 1433, 1301, 755, 741, 703, 662, 520 cm⁻¹. MS (EI) m/z (relative intensity): 211 ([M⁺] 34), 169 (100), 139 (7), 115 (5), 43 (15). HR-MS (ESI) m/z calculated for C₁₄H₁₃NO [M⁺] 211.0997, found 211.0996.

Example 2 Comp. N-([1,1′-Biphenyl]-2-yl)acetamide

The procedure was as described in Example 1, except that the reaction was conducted in THF rather than in DMF. 116 mg of N-([1,1′-biphenyl]-2-yl)acetamide were obtained as a colourless solid (55% of theory).

Example 2a N-([1,1′-Biphenyl]-2-yl)acetamide

The procedure was as described in Example 1, except that the reaction was conducted in ethyl acetate rather than in DMF. N-([1,1′-Biphenyl]-2-yl)acetamide was obtained as a colourless solid (55% of theory).

Example 2b N-([1,1′-Biphenyl]-2-yl)acetamide

The procedure was as described in Example 1, except that the reaction was conducted in methanol rather than in DMF. N-([1,1′-Biphenyl]-2-yl)acetamide was obtained as a colourless solid (70% of theory).

Example 2c N-([1,1′-Biphenyl]-2-yl)acetamide

The procedure was as described in Example 1, except that the reaction was conducted in dichloroethane rather than in DMF. N-([1,1′-Biphenyl]-2-yl)acetamide was obtained as a colourless solid (57% of theory).

Example 2d N-([1,1′-Biphenyl]-2-yl)acetamide

The procedure was as described in Example 1, except that the reaction was conducted in water rather than in DMF. N-([1,1′-Biphenyl]-2-yl)acetamide was obtained as a colourless solid (43% of theory).

Example 2e cl N-([1,1′-Biphenyl]-2-yl)acetamide

The procedure was as described in Example 1, except that the reaction was conducted in DMA rather than in DMF. N-([1,1′-Biphenyl]-2-yl)acetamide was obtained as a colourless solid (46% of theory).

Example 2f N-([1,1′-Biphenyl]-2-yl)acetamide

The procedure was as described in Example 1, except that the reaction was conducted in DME rather than in DMF. N-([1,1′-Biphenyl]-2-yl)acetamide was obtained as a colourless solid (50% of theory).

Example 2g N-([1,1′-Biphenyl]-2-yl)acetamide

The procedure was as described in Example 1, except that the reaction was conducted in a 1:1 mixture of DMF and THF rather than in DMF. N-([1,1′-Biphenyl]-2-yl)acetamide was obtained as a colourless solid (65% of theory).

Example 3a N-([1,1′-Biphenyl]-2-yl)acetamide

In a baked-out closable reaction vessel, a suspension consisting of acetanilide (135 mg, 1.0 mmol), [{RuCl₂(p-cymene)}₂] (30.6 mg, 5.0 mol %), AgSbF₆ (68.7 mg, 0.2 mmol), Ag₂O (232 mg, 1.0 mmol), Fe(OTf)₃(101 mg, 0.2 mmol) and phenylboronic acid (183 mg, 1.5 mmol) in dry DMF (3.0 ml) was stirred in a nitrogen atmosphere at 110° C. for 20 h. The reaction mixture was then diluted at room temperature with EtOAc (75 ml) and filtered through Celite and silica gel, and the filtrate was concentrated. The crude product thus obtained was purified by chromatography on silica gel (n-hexane/EtOAc: 7/3). 171 mg of N-([1,1′-biphenyl]-2-yl)acetamide were obtained as a colourless solid (81% of theory).

Example 3b N-([1,1′-Biphenyl]-2-yl)acetamide

The procedure was as described in Example 3a, except that the reaction was conducted in THF rather than in DMF. N-([1,1′-Biphenyl]-2-yl)acetamide was obtained in a yield of 56% of theory.

Example 4 N-([1,1′-Biphenyl]-2-yl)acetamide

In a baked-out closable reaction vessel, a suspension consisting of acetanilide (135 mg, 1.0 mmol), [{RuCl₂(p-cymene)}₂] (30.6 mg, 5.0 mol %), AgSbF₆ (68.7 mg, 0.2 mmol), Ag₂O (232 mg, 1.0 mmol), Cu(OTf)₂ (72.3 mg, 0.2 mmol) and diphenylborinic acid (137 mg, 0.75 mmol) in dry DMF (3.0 ml) was stirred in a nitrogen atmosphere at 110° C. for 20 h. The reaction mixture was then diluted at room temperature with EtOAc (75 ml) and filtered through Celite and silica gel, and the filtrate was concentrated. The crude product thus obtained was purified by chromatography on silica gel (n-hexane/EtOAc: 7/3). 84.4 mg of N-([1,1′-biphenyl]-2-yl)acetamide were obtained as a colourless solid (40% of theory).

Example 5 N-(4-Methyl-[1,1′-biphenyl]-2-yl)acetamide

In a baked-out closable reaction vessel, a suspension consisting of N-(m-tolyl)acetamide (149 mg, 1.0 mmol), [{RuCl₂(p-cymene)}₂] (30.6 mg, 5.0 mol %), AgSbF₆ (68.7 mg, 0.2 mmol), Ag₂O (232 mg, 1.0 mmol), Cu(OTf)₂ (72.3 mg, 0.2 mmol) and phenylboronic acid (183 mg, 1.5 mmol) in dry DMF (3.0 ml) was stirred in a nitrogen atmosphere at 110° C. for 20 h. The reaction mixture was then diluted at room temperature with EtOAc (75 ml) and filtered through Celite and silica gel, and the filtrate was concentrated. The crude product thus obtained was purified by chromatography on silica gel (n-hexane/EtOAc: 7/3). 175 mg of N-(4-methyl-[1,1′-biphenyl]-2-yl)acetamide were obtained as a colourless solid (78% of theory). M.p.=139-141° C. ¹H NMR (CDCl₃, 300 MHz): δ=8.04 (s, 1H), 7.50-7.28 (m, 5H), 7.21-7.08 (m, 2H), 6.98 (d, J=7.6 Hz, 1H), 2.38 (s, 3H), 1.98 (s, 3H). ¹³C NMR (CDCl₃, 125 MHz): δ=168.0 (C_(q)), 138.3 (C_(q)), 138.1 (C_(q)), 134.3 (C_(q)), 129.7 (CH), 129.4 (C_(q)), 129.2 (CH), 128.9 (CH), 127.6 (CH), 125.1 (CH), 122.2 (CH), 24.6 (CH₃), 21.5 (CH₃). IR (neat): 3224, 3029, 2916, 1652, 1539, 1476, 1412, 1297, 820, 763, 724, 700, 611, 524 cm⁻¹. MS (El) m/z (relative intensity): 225 ([M⁺] 54), 183 (100), 167 (30), 43 (20). HR-MS (ESI) m/z calculated for C₁₅H₁₅NO [M⁺] 225.1154, found 225.1159.

Example 6 N-(5-Methyl-[1,1′-biphenyl]-2-yl)acetamide

In a baked-out closable reaction vessel, a suspension consisting of N-(p-tolyl)acetamide (149 mg, 1.0 mmol), [{RuCl₂(p-cymene)}₂] (30.6 mg, 5.0 mol %), AgSbF₆ (68.7 mg, 0.2 mmol), Ag₂O (232 mg, 1.0 mmol), Cu(OTf)₂ (72.3 mg, 0.2 mmol) and phenylboronic acid (183 mg, 1.5 mmol) in dry DMF (3.0 ml) was stirred in a nitrogen atmosphere at 110° C. for 20 h. The reaction mixture was then diluted at room temperature with EtOAc (75 ml) and filtered through Celite and silica gel, and the filtrate was concentrated. The crude product thus obtained was purified by chromatography on silica gel (n-hexane/EtOAc: 7/3). 178 mg of N-(5-methyl-[1,1′-biphenyl]-2-yl)acetamide were obtained as a colourless solid (79% of theory). M.p.=107-109° C. ¹H NMR (CDCl₃, 300 MHz): δ=8.06 (d, J=8.3 Hz, 1H), 7.50-7.31 (m, 5H), 7.16 (dd, J=8.3, 2.2 Hz, 1H), 7.04 (m, 2H), 2.33 (s, 3H), 1.99 (s, 3H). ¹³C NMR (CDCl₃, 126 MHz): δ=168.0 (C_(q)), 138.3 (C_(q)), 134.0 (C_(q)), 132.3 (C_(q)), 132.0 (C_(q)), 131.0 (CH), 129.1 (CH), 128.9 (CH), 128.8 (CH), 127.7 (CH), 121.9 (CH), 24.5 (CH₃), 20.9 (CH₃). IR (neat): 3235, 3057, 3029, 2922, 1655, 1524, 1505, 1488, 1366, 761, 734, 691, 603, 580 cm⁻¹. MS (EI) m/z (relative intensity): 225 ([M⁺] 54), 183 (100), 167 (18), 43 (22). HR-MS (ESI) m/z calculated for C₁₅H₁₅NO [M+] 225.1154, found 225.1154.

Example 7 N-(3′,4′-Dichloro-5-fluoro-[1,1′-biphenyl]-2-yl)acetamide

In a baked-out closable reaction vessel, a suspension consisting of N-(4-fluorophenyl)acetamide (153 mg, 1.0 mmol), [{RuCl₂(p-cymene)}₂] (30.6 mg, 5.0 mol %), AgSbF₆ (68.7 mg, 0.2 mmol), Ag₂O (232 mg, 1.0 mmol), Cu(OTf)2 (72.3 mg, 0.2 mmol) and 3,4-dichlorophenylboronic acid (286 mg, 1.5 mmol) in dry DMF (3.0 ml) was stirred in a nitrogen atmosphere at 110° C. for 20 h. The reaction mixture was then diluted at room temperature with EtOAc (75 ml) and filtered through Celite and silica gel, and the filtrate was concentrated. The crude product thus obtained was purified by chromatography on silica gel (n-hexane/EtOAc: 7/3). 188 mg of N-(3′,4′-dichloro-5-fluoro-[1,1′-biphenyl]-2-yl)acetamide were obtained as a colourless solid (63% of theory). M.p.=146-148° C.¹H NMR (CDCl₃, 300 MHz): δ=8.02-7.94 (m, 1H), 7.53 (d, J=8.2 Hz, 1H), 7.44 (d, J=2.0 Hz, 1H), 7.18 (dd, J=8.2, 2.1 Hz, 1H), 7.12-7.01 (m, 1H), 6.96-6.93 (m, 2H), 2.02 (s, 3H). ¹³C NMR (CDCl₃, 75 MHz): δ=168.5 (C_(q)), 159.5 (C_(q), J_(C-F)=246.4 Hz), 137.2 (C_(q), J_(C-F)=1.6 Hz), 133.3 (C_(q)), 133.0 (C_(q), J_(C-F)=7.6 Hz), 132.8 (C_(q)), 131.0 (CH), 130.9 (CH), 130.4 (C_(q), J_(C-F)=2.7 Hz), 128.2 (CH), 125.4 (CH, J_(C-F)=8.0 Hz), 116.5 (CH, J_(C-F)=23.2 Hz), 115.7 (CH, J_(C-F)=21.9 Hz), 24.2 (CH₃). ¹⁹F NMR (282 MHz, CDCl₃) δ=−116.6 (s). IR (neat): 3242, 3190, 1652, 1529, 1472, 1371, 1183, 863, 823, 702, 685, 607, 501 cm⁻¹. MS (EI) m/z (relative intensity): 297 ([M⁺] 48), 255 (100), 219 (40), 185 (52), 157 (17), 43 (60). HR-MS (ESI) m/z calculated for C₁₄H₁₀Cl₂FNO [M⁺] 297.0123, found 297.0128.

Example 8 N-([1,1′-Biphenyl]-2-yl)acetamide

In a baked-out closable reaction vessel, a suspension consisting of acetanilide (135 mg, 1.0 mmol), [{RuCl₂(p-cymene)}₂] (30.6 mg, 5.0 mol %), AgSbF₆ (68.7 mg, 0.2 mmol), Ag₂O (232 mg, 1.0 mmol), Na(OTf) (34.4 mg, 0.2 mmol) and phenylboronic acid (183 mg, 1.5 mmol) in dry DMF (3.0 ml) was stirred in a nitrogen atmosphere at 110° C. for 20 h. The reaction mixture was then diluted at room temperature with EtOAc (75 ml) and filtered through Celite and silica gel, and the filtrate was concentrated. According to NMR analysis, the crude product thus obtained contained 65% of theory of N-([1,1′-biphenyl]-2-yl)acetamide.

Example 9 N-([1,1′-Biphenyl]-2-yl)acetamide

The procedure was as described in Example 8, except that the reaction was conducted in the presence of 0.2 mmol of Zn(OTf)₂ rather than NaOTf. N-([1,1′-Biphenyl]-2-yl)acetamide was obtained in a yield of 74% of theory.

Example 10 N-([1,1′-Biphenyl]-2-yl)acetamide

The procedure was as described in Example 8, except that the reaction was conducted in the presence of 0.2 mmol of Mn(OTf)₂ rather than NaOTf. N-([1,1′-Biphenyl]-2-yl)acetamide was obtained in a yield of 76% of theory.

Example 11 N-([1,1′-Biphenyl]-2-yl)acetamide

The procedure was as described in Example 8, except that the reaction was conducted in the presence of 0.2 mmol of Ni(OTf)₂ rather than NaOTf. N-([1,1′-Biphenyl]-2-yl)acetamide was obtained in a yield of 82% of theory.

Example 12 N-([1,1′-Biphenyl]-2-yl)acetamide

In a baked-out closable reaction vessel, a suspension consisting of acetanilide (135 mg, 1.0 mmol), [{RuCl₂(p-cymene)}₂] (30.6 mg, 5.0 mol %), AgSbF₆ (68.7 mg, 0.2 mmol), Ag₂O (232 mg, 1.0 mmol), CuSO₄ (31.9 mg, 0.2 mmol) and phenylboronic acid (183 mg, 1.5 mmol) in dry DMF (3.0 ml) was stirred in a nitrogen atmosphere at 110° C. for 20 h. The reaction mixture was then diluted at room temperature with EtOAc (75 ml) and filtered through Celite and silica gel, and the filtrate was concentrated. The crude product thus obtained was purified by chromatography on silica gel (n-hexane/EtOAc: 7/3). 91 mg of N-([1,1′-biphenyl]-2-yl)acetamide were obtained as a colourless solid (43% of theory).

Example 13 N-(3′,4′,5′-Trifluoro-[1,1′-biphenyl]-2-yl)acetamide

In a baked-out closable reaction vessel, a suspension consisting of acetanilide (135 mg, 1.0 mmol), [{RuCl₂(p-cymene)}₂] (30.6 mg, 5.0 mol %), AgSbF₆ (68.7 mg, 0.2 mmol), Ag₂O (232 mg, 1.0 mmol), Cu(OTf)₂ (72.3 mg, 0.2 mmol) and 3,4,5-trifluorophenylboronic acid (264 mg, 1.5 mmol) in dry DMF (3.0 ml) was stirred in a nitrogen atmosphere at 110° C. for 20 h. The reaction mixture was then diluted at room temperature with EtOAc (75 ml) and filtered through Celite and silica gel, and the filtrate was concentrated. The crude product thus obtained was purified by chromatography on silica gel (n-hexane/EtOAc: 7/3). 180 mg of N-(3′,4′,5′-trifluoro-[1,1′-biphenyl]-2-yl)acetamide were obtained as a colourless solid (68% of theory). M.p.=140-141° C.¹H NMR (CDCl₃, 300 MHz): δ=8.08 (d, J=8.1 Hz, 1H), 7.40 (ddd, J=8.5, 5.9, 3.1 Hz, 1H), 7.24-7.17 (m, 2H), 7.06-6.97 (m, 2H), 6.93 (s, 1H), 2.07 (s, 3H). ¹³C NMR (CDCl₃, 126 MHz): δ=168.1 (C_(q)), 151.39 (ddd, J_(C-F)=251.6, 10.0, 4.2 Hz) (C_(q)), 139.5 (dt, J_(C-F)=253.1, 15.0 Hz) (C_(q)), 134.5 (C_(q)), 134.5 (C_(q)), 130.5 (C_(q)), 129.8 (CH), 129.5 (CH), 125.1 (CH), 123.3 (CH), 113.5 (dd, J_(C-F)=16.1, 5.4 Hz) (CH), 24.3 (CH3). ¹⁹F NMR (282 MHz, CDCl₃) δ=−132-8-133.0 (m), −161.0 (tt, J_(C-F)=20.6, 6.5 Hz). IR (neat): 3263, 3040, 2934, 2864, 1660, 1526, 1483, 1417, 1359, 1278, 1241, 1036, 872, 857, 762, 695, 669, 634, 606, 547, 465 cm⁻¹. MS (EI) m/z (relative intensity): 265 ([M⁺] 29), 223 (100), 203 (16), 175 (5), 169 (5), 84 (6), 43 (41). HR-MS (ESI) m/z calculated for C₁₄H₁₀F₃NO [M⁺] 265.0714, found 265.0718.

Example 14 N-(4′-Chloro-[1,1′-biphenyl]-2-yl)acetamide

In a baked-out closable reaction vessel, a suspension consisting of acetanilide (135 mg, 1.0 mmol), [{RuCl₂(p-cymene)}₂] (30.6 mg, 5.0 mol %), AgSbF₆ (68.7 mg, 0.2 mmol), Ag₂O (232 mg, 1.0 mmol), Cu(OTf)₂ (72.3 mg, 0.2 mmol) and 4-chlorophenylboronic acid (234 mg, 1.5 mmol) in dry DMF (3.0 ml) was stirred in a nitrogen atmosphere at 110° C. for 20 h. The reaction mixture was then diluted at room temperature with EtOAc (75 ml) and filtered through Celite and silica gel, and the filtrate was concentrated. The crude product thus obtained was purified by chromatography on silica gel (n-hexane/EtOAc: 7/3). 172 mg of N-(4′-chloro-[1,1′-biphenyl]-2-yl)acetamide were obtained as a colourless solid (70% of theory).

M.p.=114-116° C.¹H NMR (CDCl₃, 300 MHz): δ=8.16 (d, J=8.2 Hz, 1H), 7.46-7.40 (m, 2H), 7.39-7.32 (m, 1H), 7.31-7.26 (m, 2H), 7.20-7.17 (m, 2H), 7.01 (s, 1H), 2.01 (s, 3H). ¹³C NMR (CDCl₃, 126 MHz): δ=168.1 (C_(q)), 136.5 (C_(q)), 134.4 (C_(q)), 134.0 (C_(q)), 131.3 (C_(q)), 130.5 (CH), 129.9 (CH), 129.1 (CH), 128.6 (CH), 124.6 (CH), 122.2 (CH), 24.6 (CH₃). IR (neat): 3247, 3031, 2924, 2854, 1635, 1527, 1369, 1283, 1086, 828, 756, 607, 530, 489 cm⁻¹. MS (EI) m/z (relative intensity): 245 ([M⁺] 35), 203 (100), 167 (43), 139 (12), 84 (17), 43 (36). HR-MS (ESI) m/z calculated for C₁₄H₁₂ClNO [M⁺] 245.0607, found 245.0599.

Example 15 N-(5-Methoxy-[1,1′-biphenyl]-2-yl)acetamide

In a baked-out closable reaction vessel, a suspension consisting of 4-methoxyacetanilide (165 mg, 1.0 mmol), [{RuCl₂(p-cymene)}₂] (30.6 mg, 5.0 mol %), AgSbF₆ (68.7 mg, 0.2 mmol), Ag₂O (232 mg, 1.0 mmol), Cu(OTf)₂ (72.3 mg, 0.2 mmol) and 4-chlorophenylboronic acid (234 mg, 1.5 mmol) in dry DMF (3.0 ml) was stirred in a nitrogen atmosphere at 110° C. for 20 h. The reaction mixture was then diluted at room temperature with EtOAc (75 ml) and filtered through Celite and silica gel, and the filtrate was concentrated. The crude product thus obtained was purified by chromatography on silica gel (n-hexane/EtOAc: 7/3). 183 mg of N-(5-methoxy-[1,1′-biphenyl]-2-yl)acetamide were obtained as a colourless solid (76% of theory). M.p.=112-114° C. NMR (CDCl₃, 300 MHz): δ=7.95 (d, J=8.9 Hz, 1H), 7.50-7.28 (m, 5H), 6.98 (s, 1H), 6.88 (dd, J=8.9, 3.0 Hz, 1H), 6.78 (d, J=3.0 Hz, 1H), 3.78 (s, 3H), 1.97 (s, 3H). ¹³C NMR (CDCl₃, 126 MHz): δ=168.2 (C_(q)), 156.3 (C_(q)), 138.1 (C_(q)), 134.7 (C_(q)), 128.9 (CH), 128.8 (CH), 127.8 (CH), 127.6 (C_(q)), 124.3 (CH), 115.3 (CH), 113.3 (CH), 55.5 (CH₃), 24.2 (CH₃).

IR (neat): 3263, 3058, 2969, 2939, 2838, 1664, 1480, 1270, 1207, 1178, 1033, 701, 599, 512 cm⁻¹. MS (El) m/z (relative intensity): 241 ([M⁺]71), 199 (76), 184 (100), 154 (21), 128 (11), 43 (34). HR-MS (ESI) m/z calculated for C₁₅H₁₅NO₂ [M⁺] 241.1103, found 241.1106.

Example 16 N-(4-Methoxy-[1,1′-biphenyl]-2-yl)acetamide

In a baked-out closable reaction vessel, a suspension consisting of 3-methoxyacetanilide (165 mg, 1.0 mmol), [{RuCl₂(p-cymene)}₂] (30.6 mg, 5.0 mol %), AgSbF₆ (68.7 mg, 0.2 mmol), Ag₂O (232 mg, 1.0 mmol), Cu(OTf)₂ (72.3 mg, 0.2 mmol) and 4-chlorophenylboronic acid (234 mg, 1.5 mmol) in dry DMF (3.0 ml) was stirred in a nitrogen atmosphere at 110° C. for 20 h. The reaction mixture was then diluted at room temperature with EtOAc (75 ml) and filtered through Celite and silica gel, and the filtrate was concentrated. The crude product thus obtained was purified by chromatography on silica gel (n-hexane/EtOAc: 7/3). 174 mg of N-(4-methoxy-[1,1′-biphenyl]-2-yl)acetamide were obtained as a colourless solid (72% of theory). M.p.=91-93° C. ¹H NMR (CDCl₃, 300 MHz): δ=7.98 (d, J=2.6 Hz, 1H), 7.49-7.42 (m, 2H), 7.40-7.36 (m, 1H), 7.35-7.32 (m, 1H), 7.32-7.29 (m, 1H), 7.17 (s, 1H), 7.12 (d, J=8.5 Hz, 1H), 6.72 (dd, J=8.5, 2.6 Hz, 1H), 3.84 (s, 3H), 2.00 (s, 3H). ¹³C NMR (CDCl₃, 126 MHz): δ=168.1 (C_(q)), 159.4 (C_(q)), 137.9 (C_(q)), 135.6 (C_(q)), 130.6 (CH), 129.3 (CH), 129.0 (CH), 127.6 (CH), 124.2 (C_(q)), 110.5 (CH), 106.2 (CH), 55.5 (CH₃), 24.8 (CH₃). IR (neat): 3415, 3241, 3033, 2953, 2831, 1652, 1309, 1233, 762, 724, 698, 621, 525 cm’. MS (El) m/z (relative intensity): 241 ([M⁺] 74), 199 (100), 170 (16), 156 (19), 84 (9), 43 (34). HR-MS (ESI) m/z calculated for C₁₅H₁₅NO₂ [M⁺] 241.1103, found 241.1107.

Example 17 N-(5-Ethyl-[1,1′-biphenyl]-2-yl)acetamide

In a baked-out closable reaction vessel, a suspension consisting of 4-ethylacetanilide (163 mg, 1.0 mmol), [{RuCl₂(p-cymene)}₂] (30.6 mg, 5.0 mol %), AgSbF₆ (68.7 mg, 0.2 mmol), Ag₂O (232 mg, 1.0 mmol), Cu(OTf)₂ (72.3 mg, 0.2 mmol) and phenylboronic acid (183 mg, 1.5 mmol) in dry DMF (3.0 ml) was stirred in a nitrogen atmosphere at 110° C. for 20 h. The reaction mixture was then diluted at room temperature with EtOAc (75 ml) and filtered through Celite and silica gel, and the filtrate was concentrated. The crude product thus obtained was purified by chromatography on silica gel (n-hexane/EtOAc: 7/3). 151 mg of N-(5-ethyl-[1,1′-biphenyl]-2-yl)acetamide were obtained as a colourless solid (63% of theory). M.p.=64-65° C.¹H NMR (CDCl₃, 300 MHz): δ=8.07 (d, J=8.3 Hz, 1H), 7.54-7.31 (m, 5H), 7.20 (dd, J=8.3, 2.3 Hz, 1H), 7.13 (s, 1H), 7.09 (d, J=2.3 Hz, 1H), 2.65 (q, J=7.6 Hz, 2H), 2.00 (s, 3H), 1.25 (t, J=7.6 Hz, 3H). ¹³C NMR (CDCl₃, 126 MHz): δ=168.0 (C_(q)), 140.3 (C_(q)), 138.3 (C_(q)), 132.5 (C_(q)), 132.1 (C_(q)), 129.3 (CH), 129.0 (CH), 128.8 (CH), 127.6 (CH), 127.5 (CH), 122.2 (CH), 28.3 (CH2), 24.4 (CH₃), 15.6 (CH₃). IR (neat): 3424, 3267, 3027, 2964, 2930, 2871, 1659, 1513, 1487, 1410, 1368, 1297, 767, 699, 509 cm⁻¹. MS (EI) m/z (relative intensity): 239 ([M⁺] 58), 197 (58), 182 (100), 180 (19), 167 (16), 43 (37). HR-MS (ESI) m/z calculated for C₁₆H₁₇NO [M⁺] 239.1310, found 239.1306.

Example 18 N-(5-Hydroxy-[1,1′-biphenyl]-2-yl)acetamide

In a baked-out closable reaction vessel, a suspension consisting of 4-hydroxyacetanilide (151 mg, 1.0 mmol), [{RuCl₂(p-cymene)}₂] (30.6 mg, 5.0 mol %), AgSbF₆ (68.7 mg, 0.2 mmol), Ag₂O (232 mg, 1.0 mmol), Cu(OTf)₂ (72.3 mg, 0.2 mmol) and phenylboronic acid (183 mg, 1.5 mmol) in dry DMF (3.0 ml) was stirred in a nitrogen atmosphere at 110° C. for 20 h. The reaction mixture was then diluted at room temperature with EtOAc (75 ml) and filtered through Celite and silica gel, and the filtrate was concentrated. The crude product thus obtained was purified by chromatography on silica gel (n-hexane/EtOAc: 7/3). 157 mg of N-(5-hydroxy-[1,1′-biphenyl]-2-yl)acetamide were obtained as a colourless solid (69% of theory). NMR (CDCl₃, 300 MHz): δ=7.59 (d, J=9.5 Hz, 1H), 7.53 (s, 1H), 7.43-7.32 (m, 3H), 7.30-7.24 (m, 2H), 7.05 (s, 1H), 6.73-6.67 (m, 2H), 1.99 (s, 3H). ¹³C NMR (CDCl₃, 126 MHz): δ=169.7 (C_(q)), 154.1 (C_(q)), 138.1 (C_(q)), 136.1 (C_(q)), 128.8 (CH), 128.6 (CH), 127.6 (CH), 126.0 (C_(q)), 125.7 (CH), 117.1 (CH), 115.3 (CH), 23.9 (CH₃). IR (neat): 3268, 3057, 2959, 2926, 2795, 1524, 1488, 1433, 1299, 1199, 726, 699, 646, 506 cm⁻¹. MS (El) m/z (relative intensity): 227 ([M⁺] 44), 185 (100), 154 (11), 43 (14). HR-MS (ESI) m/z calculated for C₁₄H₁₃NO₂ [M⁺] 227.0946, found 227.0945.

Example 19 N-(4′-Methyl-[1,1′-biphenyl]-2-yl)acetamide

In a baked-out closable reaction vessel, a suspension consisting of acetanilide (135 mg, 1.0 mmol), [{RuCl₂(p-cymene)}₂] (30.6 mg, 5.0 mol %), AgSbF₆ (68.7 mg, 0.2 mmol), Ag₂O (232 mg, 1.0 mmol), Cu(OTf)₂ (72.3 mg, 0.2 mmol) and 4-methylphenylboronic acid (204 mg, 1.5 mmol) in dry DMF (3.0 ml) was stirred in a nitrogen atmosphere at 110° C. for 20 h. The reaction mixture was then diluted at room temperature with EtOAc (75 ml) and filtered through Celite and silica gel, and the filtrate was concentrated. The crude product thus obtained was purified by chromatography on silica gel (n-hexane/EtOAc: 7/3). 185 mg of N-(4′-methyl[1,1′-biphenyl]-2-yl)acetamide were obtained as a colourless solid (82% of theory). M.p.=106-108° C. ¹H NMR (CDCl₃, 300 MHz): δ=8.24 (d, J=8.2 Hz, 1H), 7.44-7.06 (m, 8H), 2.41 (s, 3H), 2.01 (s, 3H). ¹³C NMR (CDCl₃, 126 MHz): δ=168.0 (C_(q)), 137.6 (C_(q)), 135.0 (C_(q)), 134.6 (C_(q)), 132.0 (C_(q)), 130.0 (CH), 129.7 (CH), 128.9 (CH), 128.1 (CH), 124.1 (CH), 121.4 (CH), 24.6 (CH₃), 21.2 (CH₃). IR (neat): 3340, 2956, 2921, 2853, 1515, 1442, 1282, 817, 756, 680, 598, 522, 488 cm⁻¹. MS (EI) m/z (relative intensity): 225 ([M⁺] 55), 183 (100), 167 (37), 43 (26). HR-MS (ESI) m/z calculated for C₁₅H₁₅NO [M⁺] 225.1154, found 225.1149.

Example 20 N-(4′-Methoxy-[1,1′-biphenyl]-2-yl)acetamide

In a baked-out closable reaction vessel, a suspension consisting of acetanilide (135 mg, 1.0 mmol), [{RuCl₂(p-cymene)}₂] (30.6 mg, 5.0 mol %), AgSbF₆ (68.7 mg, 0.2 mmol), Ag₂O (232 mg, 1.0 mmol), Cu(OTf)₂ (72.3 mg, 0.2 mmol) and 4-methoxyphenylboronic acid (228 mg, 1.5 mmol) in dry DMF (3.0 ml) was stirred in a nitrogen atmosphere at 110° C. for 20 h. The reaction mixture was then diluted at room temperature with EtOAc (75 ml) and filtered through Celite and silica gel, and the filtrate was concentrated. The crude product thus obtained was purified by chromatography on silica gel (n-hexane/EtOAc: 7/3). 200 mg of N-(4′-methyl[1,1′-biphenyl]-2-yl)acetamide were obtained as a colourless solid (83% of theory). M.p.=135-137° C. ¹H NMR (CDCl₃, 300 MHz): δ=8.20 (d, J=8.2 Hz, 1H), 7.34-7.24 (m, 3H), 7.23-7.09 (m, 3H), 6.98 (d, J=8.6 Hz, 2H), 3.84 (s, 3H), 2.00 (s, 3H). ¹³C NMR (CDCl₃, 126 MHz): δ=168.3 (C_(q)), 159.3 (C_(q)), 134.8 (C_(q)), 132.0 (C_(q)), 130.3 (CH), 130.2 (C_(q)), 130.1 (CH), 128.0 (CH), 124.3 (CH), 121.6 (CH), 114.4 (CH), 55.2 (CH₃), 24.4 (CH₃). IR (neat): 3351, 3012, 2921, 2842, 1690, 1602, 1512, 1439, 1362, 1294, 1239, 1175, 1031, 832, 800, 770, 663, 581, 560, 534 cm⁻¹. MS (EI) m/z (relative intensity): 241 ([M⁺] 54), 199 (100), 184 (37), 154 (24), 128 (12), 43 (30). HR-MS (ESI) m/z calculated for C₁₅H₁₅NO₂ [M⁺] 241.1103, found 241.1110.

Example 21 N-(Biphenyl-2-yl)-2-methylpropanamide

In a baked-out closable reaction vessel, a suspension consisting of 2-methyl-N-phenylpropanamide (163 mg, 1.0 mmol), [{RuCl₂(p-cymene)}₂]0 (30.6 mg, 5.0 mol %), AgSbF₆ (68.7 mg, 0.2 mmol), Ag₂O (232 mg, 1.0 mmol), Cu(OTf)₂ (72.3 mg, 0.2 mmol) and phenylboronic acid (183 mg, 1.5 mmol) in dry DMF (3.0 ml) was stirred in a nitrogen atmosphere at 110° C. for 20 h. The reaction mixture was then diluted at room temperature with EtOAc (75 ml) and filtered through Celite and silica gel, and the filtrate was concentrated. The crude product thus obtained was purified by chromatography on silica gel (n-hexane/EtOAc: 7/3). 131 mg of N-(biphenyl-2-yl)-2-methylpropanamide were obtained as a colourless solid (55% of theory). M.p.=126-128° C. ¹H NMR (CDCl₃, 300 MHz): δ=8.33 (d, J=8.2 Hz, 1H), 7.54-7.33 (m, 6H), 7.28-7.13 (m, 3H), 2.4 (kept, J=6.8 Hz, 1H), 1.2 (d, J=6.8 Hz, 6H). ¹³C NMR (CDCl₃, 126 MHz): δ=174.8 (C_(q)), 138.1 (C_(q)), 134.9 (C_(q)), 132.1 (C_(q)), 129.9 (CH), 129.3 (CH), 129.0 (CH), 128.4 (CH), 128.0 (CH), 124.0 (CH), 121.3 (CH), 36.7 (CH), 19.3 (CH3). IR (neat): 3218, 2964, 1649, 1520, 1480, 1239, 1203, 1099, 776, 748, 726, 702, 542 cm⁻¹. MS (EI) m/z (relative intensity): 239 ([M⁺] 29), 169 (100), 71 (6), 43 (30). HR-MS (ESI) m/z calculated for C₁₆H₁₇NO [M⁺] 239.1310, found 239.1314.

Example 22 N-(Biphenyl-2-yl)-2,2-dimethylpropanamide

In a baked-out closable reaction vessel, a suspension consisting of 2,2-dimethyl-N-phenylpropanamide (177 mg, 1.0 mmol), [{RuCl₂(p-cymene)}₂] (30.6 mg, 5.0 mol %), AgSbF₆ (68.7 mg, 0.2 mmol), Ag₂O (232 mg, 1.0 mmol), Cu(OTf)₂ (72.3 mg, 0.2 mmol) and phenylboronic acid (183 mg, 1.5 mmol) in dry DMF (3.0 ml) was stirred in a nitrogen atmosphere at 110° C. for 20 h. The reaction mixture was then diluted at room temperature with EtOAc (75 ml) and filtered through Celite and silica gel, and the filtrate was concentrated. The crude product thus obtained was purified by chromatography on silica gel (n-hexane/EtOAc: 7/3). 114 mg of N-(biphenyl-2-yl)-2,2-dimethylpropanamide were obtained as a colourless solid (45% of theory). M.p.=68-69° C. ¹H NMR (CDCl₃, 300 MHz): δ=8.37 (dd, J=8.2, 1.2 Hz, 1H), 7.54-7.33 (m, 7H), 7.24 (dd, J=7.4, 1.7 Hz, 1H), 7.17 (dd, J=7.4, 1.7 Hz, 1H), 1.09 (s, 9H). ¹³C NMR (CDCl₃, 126 MHz): δ=176.1 (C_(q)), 138.0 (C_(q)), 135.0 (C_(q)), 132.0 (C_(q)), 129.6 (CH), 129.2 (CH), 128.9 (CH), 128.4 (CH), 127.9 (CH), 123.8 (CH), 120.8 (CH), 39.8 (C_(q)), 27.4 (CH₃). IR (neat): 3259, 3056, 2970, 2904, 2868, 1646, 1503, 1477, 771, 743, 700, 647 cm⁻¹. MS (EI) m/z (relative intensity): 253 ([M⁺] 53), 169 (60), 57 (100), 41 (17). HR-MS (ESI) m/z calculated for C₁₇H₁₉NO [M⁺] 253.1467, found 253.1472. 

1. A process for preparing one or more biphenylamides of formula (Ia)

(Ia) in which R¹ is hydrogen, hydroxyl, fluorine, chlorine, C₁-C₄-alkyl, C₁-C₄-alkoxy, C₁-C₄-alkylthio or C₁-C₄-haloalkyl, R² is C₁-C₄-alkyl, C₆-C₁₀-aryl or C₆-C₁₀-aryl-CH₂—, and X¹ is hydrogen, C₁-C₃-alkyl, C₁-C₄-alkoxy, fluorine or chlorine, X² is hydrogen, C₁-C₃-alkyl, C₁-C₄-alkoxy, fluorine or chlorine, X³ is hydrogen, C₁-C₃-alkyl, C₁-C₄-alkoxy, fluorine or chlorine, comprising reacting one or more anilides of formula (II)

in which R¹ and R² are each as defined above, with an organoboron compound of formula (III)

in which X¹, X² and X³ are each as defined above, and which is selected from one of the following groups consisting of: (i) boronic acids of formula (III) in which Q is a hydroxyl group, m is 2, p is 1, or the anhydrides, dimers or trimers of these boronic acids; (II) boronic acid derivatives of formula (III) in which Q is F, Cl, Br, I, C₁-C₄-alkyl, C₆-C₁₀-aryl, C₁-C₄-alkoxy or C₆-C₁₀-aryloxy, m is 2, p is 1; (III) borinic acids of formula (III) in which Q is OH, F, Cl, Br, I, C₁-C₄-alkyl, C₆-C₁₀-aryl, C₁-C₄-alkoxy or C₆-C₁₀-aryloxy, m is 1, p is 2; (IV) cyclic boronic esters of formula (III) in which Q is a C₂-C₃-alkyldioxy radical which, together with the boron atom to which it is bonded, forms a 5- or 6-membered ring optionally substituted by one or more C₁-C₄-alkyl radicals, m is 2, p is 1; (V) boronates of formula (III) in which Q is OH, F, Cl, Br, I, C₁-C₄-alkyl, C₆-C₁₀-aryl, C₁-C₄-alkoxy or C₆-C₁₀-aryloxy, m is 3, p is 1 and the negative charge of the boronate anion is compensated for by a cation, (VI) triarylboranes of formula (III) in which m is 0, p is 3; (VII) tetraarylborates of formula (IV) in which m is 0, p is 4 and the negative charge of the tetraarylborate anion is compensated for by a cation, in the presence of a catalyst system consisting of a ruthenium catalyst, an activator, an oxidizing agent and a metal sulphate. 